Strange percentage behaviour after recharge

[Rapax]

The other day, I recharged from 26% to 79%. I usually recharge from 50-80%. The thing is, since I recharged, the percentages are dropping very slowly. Meaning, after driving 65km, it dropped just 12%. It's now at 67%. In these winter conditions, that's impossible consumption. Normally, it would be close to 20%. Driving style and route is the same.
Like battery got rebalanced and gained kw LOL.
Thing is, I do balancing charge once in a while to 100%.
Has anyone else encountered this 'phenomenon'?

 

[ReintjeWA]

Do you sometimes let I go down to below 10% and then charge in one go to 100%? I believe this lets the car see how much capacity the battery currently holds, or “how deep the well is”. If I’m not mistaken it’s referred to as calibrating the BMS.

 

[webhiker]

You probably have reached 1000 hours on the total trip counter or you have (accidently) reset it.
The total trip counter carries the element of drivers drive style in GoM
Just guessing

 

[Rapax]

You probably have reached 1000 hours on the total trip counter or you have (accidently) reset it.
The total trip counter carries the element of drivers drive style in GoM
Just guessing

No it's not reset. And even if reset, it would just reset guesometer, not actual percentage level.

Do you sometimes let I go down to below 10% and then charge in one go to 100%? I believe this lets the car see how much capacity the battery currently holds, or “how deep the well is”. If I’m not mistaken it’s referred to as calibrating the BMS.

Very rarely, and it should calibrate BMS when you go to 100% and leave it balancing itself.
I have looked one tesla owner done it from 1% to 100% to rebalance. Obviously we should do the same. Or I have some glitch in the system.

 

[ReintjeWA]

As I understand it the <10%-100% is different from balancing the battery cells at 100%. Also the NMC battery packs will balance cells at any charge level set in the car or app, not just 100%.

Regardless I would expect the car to be more cautious and consume more % per distance driven if it hasn’t seen the full capacity for a while, whereas what you describe sounds like the car thinks it has a bigger battery then it does?

I actually noticed this today after doing a balance at 100%, which I don’t do often as I rely mostly on public charging. When the aircon is set to off, and eco mode selected (both things I normally don’t have set like this) the car guesstimates more than the 435km WLTP range, even though the total trip counter hasn’t reset yet.

With the aircon on and drive mode set to normal it shows 401km which is what I have come to expect at 100% when mostly driving my daily commute.

 

[Rapax]

Yes. My ER thinks he have 100kw battery pack hahaha.

 

[JonnyG]

.........Has anyone else encountered this 'phenomenon'?

Yes, I've had this very occasionally (over 11,000 miles). The first time I even thought the GoM had got stuck as it stayed on the same percentage for around 10 miles with the heating on too ! It seems to fix itself over time for me

 

[Tuareg]

My Xpower always shows around 430/435kms range when fully charged to 100% same battery as the LR.

 

[CuriousIslander]

I get something similar I think. I usually charge (at home) to 90%. Then I regularly see that the car goes about 35 miles in dropping to 80%, equivalent to a total range of 350 miles, which is clearly nonsense, particularly at this time of year. However as the battery runs down the consumption gradually increases, so that by the time it has dropped to 50% the equivalent total range is about 250 miles at this time of year. If I let the battery drop to 40% this comes down to about 240 miles, and so it goes on.

What I really would like to know is whether the battery really is much more efficient at higher states of charge, and if so, is there anything to be gained by charging it up to 90% more-or-less every other day. I do about 120 miles a week on average, just pottering about - going to golf, orchestra rehearsal and the like. I very occasionally run the battery down much lower, usually to the teens% and then do a charge, with a 100% charge if I do a rare mainland excursion, or at about every 6 weeks.

I find the whole subject of battery usage quite interesting (nerd that I am) and I always try to get the most out of it with conservative driving.

 

[QLeo]

The other day, I recharged from 26% to 79%. I usually recharge from 50-80%. The thing is, since I recharged, the percentages are dropping very slowly. Meaning, after driving 65km, it dropped just 12%. It's now at 67%. In these winter conditions, that's impossible consumption. Normally, it would be close to 20%. Driving style and route is the same.
Like battery got rebalanced and gained kw LOL.
Thing is, I do balancing charge once in a while to 100%.
Has anyone else encountered this 'phenomenon'?

Some time back we had something similar. We topped up somewhere - can't recall the percentage - but it stayed displaying that percentage for about 40 miles and then dropped away. We concluded that the display was wrong - that the actual percentage was higher, and eventually caught up with itself. It's only ever happened the once, and that was with the previous software version, before that little white stripe on the green of the percentage bar.

 

[Rapax]

... it stayed on the same percentage for around 10 miles with the heating on too ! It seems to fix itself over time for me

Yes, same thing here. I had 15km without percentage change.
I'm at 9.000km now, and this is the first time experiencing this glitch.

What I really would like to know is whether the battery really is much more efficient at higher states of charge.

Percentage drop is not linear in MG4.

 

[Rapax]

I would like to thank everyone who replied. It's easier knowing I'm not the only one with this glitch. This forum is really a wonderful place

 

[dsimpkins]

I once had an issue after using a rapid charger in that the battery percentage didn't change at all, even after driving for a couple of days. It rectified itself after I slow charged to 100%.

 

[Koops]

The other day, I recharged from 26% to 79%. I usually recharge from 50-80%. The thing is, since I recharged, the percentages are dropping very slowly. Meaning, after driving 65km, it dropped just 12%. It's now at 67%. In these winter conditions, that's impossible consumption. Normally, it would be close to 20%. Driving style and route is the same.
Like battery got rebalanced and gained kw LOL.
Thing is, I do balancing charge once in a while to 100%.
Has anyone else encountered this 'phenomenon'?

I get this with my 2024 Long Range, where the battery state changes little from the 80% charge for 15-20km, then it seems to drop quickly to the expected discharge.